Formation of Intermetallic Compounds on Refractory Metals in Aluminum-Silicon Liquid

Publisher Summary This chapter explores that for energy serving and ecological issue, an increase in operation temperature of gas turbine systems has been required to increase energy conversion efficiency. New high temperature materials have been required with higher applicable temperatures than that of Ni based superalloys. Disilicides such as MoSi 2 has a promising material because of excellent resistance for high temperature oxidation. Since MoSi 2 has low creep strength and high temperature strength, the intermetallic compound is reasonable for application of coating to prohibit high temperature Oxidation. Dipping the refracto U metals, Mo and Nb, into molten A1 liquid saturating Si, aluminodisilicides were formed on the surface of the metals. The existence of A1 and Si at the grain boundary of the intermetallic layer and the interface between the refractory metals and the intermetallic layer was revealed from the results of detail observation and electron probe microanalysis (EPMA). The supply of AI and Si is carried out by passing the A1-Si liquid at the grain boundary. The reaction for the formation of alumino-disilicide occurs at the A1-Si liquid at the interface between the refractory metals and the intermetallics.